Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;

int main() {
  int H, W;
  cin >> H >> W;
  vector<string> s(H);
  for(auto& i: s) cin >> i;

  auto sum=0;
  for(auto i: s) for(auto j: i) if(j=='#') ++sum;

  const vector<int> dy = {0, 1, 0, -1};
  const vector<int> dx = {1, 0, -1, 0};

  vector<vector<int>> d(H, vector<int>(W, -1));
  queue<pair<int,int>> q;
  q.emplace(0,0);
  d[0][0] = 1;
  while(!q.empty()) {
    auto y = q.front().first;
    auto x = q.front().second;
    q.pop();
    for(auto i=0; i<4; ++i) {
      auto ny = y+dy[i];
      auto nx = x+dx[i];
      if(ny<0||H<=ny) continue;
      if(nx<0||W<=nx) continue;
      if(d[ny][nx]!=-1) continue;
      if(s[ny][nx]=='#') continue;
      d[ny][nx] = d[y][x] + 1;
      q.emplace(ny, nx);
    }
  }
  if(d[H-1][W-1]==-1) cout << -1 << endl;
  else                cout << H*W - d[H-1][W-1] - sum << endl;
}